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A pilot is invited to have a session in a spatial disorientation training device. Such a device can rotate around any of its 3 axes (or multiple at once), and the pilot has no visual reference to the outside. When the device is rotating around only the vertical axis (yawing), the pilot is asked to nod their head up and down. They very quickly become dizzy and disorientated. Why does this happen?
  • A
    Without any outside visual references, the interaction between their individual senses becomes disturbed by nodding their head while the device is rotating.
  • B
    The dizziness and disorientation is caused solely by the rotation of the device without external visual reference, the nodding of the head does not influence this effect.
  • C
    The process of interpreting vestibular sensations in the brain's cerebral cortex is adversely affected by the pilot nodding their head, leading to disorientation.
  • D
    The nodding of the head disturbs the equilibrium of all the sensory inputs. This can be compensated for by the brain for a certain time, after which, disorientation will begin.

This is a really lengthy question with lots of words to try and confuse you. We are currently unsure of the wording, so please let us know if you get this question in your exam and whatever you are able to remember about it, thank you!

The question is referring to the coriolis illusion. This is what we feel when our semicircular canals all sense movement at once, which the brain cannot explain. It is quite a bit more complex than this, but for our purposes, it is what happens when a pilot bends down to pick up a pen during a turn. The pilot's vestibular senses have become accustomed to the turn, but when the pilot's head moves and rotates, the equilibrium in all the semicircular canals is disrupted immediately. This leads to dizziness, a tumbling sensation and significant disorientation, particularly if visual reference is lost. The best way to fix these symptoms is to minimise head movements and fixate on the external visual situation or the instruments to allow the brain to understand the situation.


Let's go through each option:

  • "Without any outside visual references, the interaction between their individual senses becomes disturbed by nodding their head while the device is rotating."
    • This is correct. "the interaction between individual senses" is referring to the different semicircular canals all getting simultaneous angular accelerations at once, which the brain cannot handle. It is important to notice also that this option mentions that nodding the head whilst the device is rotating causes this illusion, and this is because those rotations are occurring around different axes. Just one rotation would quickly get understood by the particular semicircular canal, but when equilibrium has been reached (device spinning), then a different rotation is introduced, all the canals experience new angular accelerations, and without visual reference, the brain gets immediately disorientated.
  • "The dizziness and disorientation is caused solely by the rotation of the device without external visual reference, the nodding of the head does not influence this effect."
    • No. As mentioned above, the head nodding on a different axis to the device spinning causes the illusion, the spinning is not enough on its own.
  • "The process of interpreting vestibular sensations in the brain's cerebral cortex is adversely affected by the pilot nodding their head, leading to disorientation."
    • The process of interpreting vestibular sensations does not occur in the cerebral cortex, and it is not the interpretation that is disrupted, it is the physical movements within the semicircular canals.
  • "The nodding of the head disturbs the equilibrium of all the sensory inputs. This can be compensated for by the brain for a certain time, after which, disorientation will begin."
    • As far as we can tell, the brain cannot "compensate" for the coriolis illusion at all, the effects are immediate. We are also unsure about the wording of this option in the real exam, so it may be different than it is here.

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This question has appeared on the real examination, you can find the related countries below.